Key selector switch for telephone sets

ABSTRACT

A key selector switch is disclosed for use in telephone sets, said switch including a plurality of keys, each including a restoring spring. Each key also includes at least one switching nose which cooperates with a row of balls to accomplish the blocking of the keys neighboring an operated key.

Umted States Patent 11 1 1111 3,903,381

Diehr Sept. 2, 1975 [541 KEY SELECTOR SWITCH FOR 3,719,786 3 1973 Mallett ct a1. 200/5 EB TELEPHONE SETS 3,732,476 5/1973 Cairelli .1 ZOO/5 E X 3,781,497 12 1973 Stephenson ct al. 200/159 A X [75] Inventor: Helmut DIehr, Berlm, Germany 3 ,1 9 1974 K us 200/16 D x [73] Assigneez Bosse Telefonbau GmbH, Berlin, 3,845,255 10/1974 ZIelke 200 5 EA ermany FOREIGN PATENTS OR APPLICATIONS [221 F1169 June 1974 603,924 6/1948 United Kingdom 200 5 EA [2U pp NO: 479 927 1,171,150 11/1969 United Kingdom ZOO/5 EA 2,015,008 12/1970 Germany 200/5 EA Foreign Application Priority Data w Aug. 2, 1973 Germany 2339101 Pnmary b'mmmer james Scott [52] US. Cl 200/5 R; ZOO/5 E; 200/5 EA;

200/16 B; 200/ C; 74/483 PB; 235/ R lnt. C13. HOIH 9/26; GOSG 11/00; 006C 7/04 Field of Search 200/5 R, 5 E, 5 EA, 5 EB,

200/50 C, 16 B, 16 D,l62, 163,159 R, 159

A, 242, 292; 197/98; 235/145 R; 74/483 R,

ABSTRACT A key selector switch is disclosed for use in telephone sets, said switch including a plurality of keys, each including a restoring spring. Each key also includes at 483 PB least one switching nose which cooperates with a row of balls to accomplish the blocking of the keys neigh- [56] References Cited bormg an operated key.

UNITED STATES PATENTS 10 Claims, 9 Drawing Figures 3,551,611 12/1970 Fechncr ZOO/5 EA s 4 '9 l '9 4] m -8 4 1 [7 Y J l I 5 1 J .3 1, B ,1 I] B PNENTEUSED 2J5 saw u u; 4

KEY SELECTOR SWITCH FOR TELEPHONE SETS BACKGROUND OF THE INVENTION The present invention concerns a key selector switch for telephone sets, wherein a number of keys provided each with a restoring spring form a selecting unit in that said keys as well as all the pertinent component parts are accommodated in a housing. The shanks of the keys are guided in the correspondingly perforated cover of said housing and the bottom member of said housing serves as a support for the restoring springs.

Mechanical key selector switches of known designs can be subdivided into three groups differing as follows:

Group 1; The coding contact elements are associated individually to each of the keys. Upon key operation, the electrical connections are established directly. A blocking against a simultaneous operation of several keys is not known.

Group 2: Special switching units are provided outside the keyboard. Upon key operation, levers or bars are moved and perform switching work. A key blocking is usual with this mode of design and is ef fected by the mechanically moved parts. See in this respect German unexamined published patent applications, Offenlegungsschrift Nos. 2,1 19,910 and Group 3: Mechanical key arrangement with electronic coding. In accordance with, e.g., German Offenlegungsschrift No. 2,223,607 each key of a usual keyboard has a capacitor associated with it, the capacitance of said capacitor being varied upon operation of the key. Through the associated ca pacitor, each key is thus connected to an electronic switching circuit which is provided with threshold switches controlled in dependency on the capacitance.

The present invention was based on the problem of providing a key selector switch whose contact elements are non-adjustable and insertably associated with the keys. The type of contact should determine the ar rangement and number of the contacts. The actuation of the different switching contacts with one key selector switch should take place according to a fixed sequence. The coding should be effected by associating the contacts with a connecting pattern. A blocking of all the keys neighbored to the operated key should take place in a most simple way. The key selector switch should be suited for most different applications, such as, e.g., in multi-frequency systems, diode grounding systems, for deviating selecting purposes and data input by means of the same keyboard. Moreover, it is required that the unit should be very flat and exchangeable for competitive products.

SUMMARY OF THE INVENTION In accordance with the invention, these problems are solved by providing each key with an associated contact element inserted so as to be non-adjustable and self-holding. The keyboard consists of three parallel series of four keys each, each key including at least one switching nose which projects horizontally and at right angles in the housing into the spaces between the three series of keys. Upon operation of a key, the switching nose associated therewith acts on one of two balls provided in rows in the spaces between the keys such that the switching noses displace all of the remaining balls of a row by half a ball diameter in one direction and thereby causes a blocking of all the keys neighbored to the actuated key.

Further in accordance with the invention, each of the middle series of keys includes a switching nose on either side, said switching noses projecting into the spaces between the middle and outer series of keys and each of the keys of the outer series includes a switching nose, displaced by one ball diameter, projecting into said spaces in parallel to the switching noses on said middle series of keys.

The solution according to the invention renders it possible that, on the one hand, the key stroke or key travel actuates the switching contacts associated with the keys and that, on the other hand, in another switching plane, the transmission of said stroke or travel actuates, e.g., microswitches to release or change over pulses. The construction and its elements ensure an adjustment-free operating sequence between coding, key blocking, coding release and key restoring or resetting. The key blocking is attained here without additional expenditure of mechanical parts and without requiring space.

BRIEF DESCRIPTION OF THE DRAWINGS An exemplified embodiment of the invention will be described below by means of the drawings in which:

FIG. 1 is a top view of the complete key selector switch in full size;

FIG. 2 is a side elevational view of the key selector switch of FIG. 1;

FIG. 3 is a top view of the key selector switch;

FIG. 4 is an enlarged bottom view of the key selector switch, with the bottom member being removed;

FIG. 5 is a side elevational sectional enlarged view of the key selector switch, with the bottom member put on, the section being in parallel to a row of balls;

FIG. 6 is another enlarged side elevational partial sectional view, the section passing through two keys and both rows of balls;

FIG. 7 is a top view of one version of the cliplike contact elements disposed on the insulating pins; and

FIG. 8 is a top view of another design of the contact elements.

FIG. 9 is a side elevational sectional enlarged view of the key selector switch, with the bottom member put on, showing the actuation of the microswitches.

DESCRIPTION OF THE PREFERRED EMBODIMENT As is shown in FIGS. 1 and 2 in full size, the key selector switch is composed of keys 1 in the keyboard 4 as well as of the bottom member 16. The arrangement of the keys in three vertical rows having four keys 1 each corresponds to conventional designs.

It is evident from FIG. 3 in what way the switching noses 2 covered by the keyboard 4 and therefore shown in dashed lines project into the spaces between the three series of keys comprising four keys each. The switching noses 2 each of two neighboring series of keys are arranged in parallel there.

It may readily be seen from FIGS. 4 and 5 in what way the switching noses 2 cooperate with the rows of balls 10 visible in FIGS. 4 and 5 and disposed in the afore-mentioned spaces. FIG. 4 shows a row of balls in a part-sectional bottom view. The side elevational sectional view of FIG. 5 shows the bcvels 18 at the switching noses 2, said bevels 18 having the effect that, whenever any one of keys 1 is operated or depressed, a more or less great number of balls of the row of balls 10 is displaced opposite to the direction of bevel 18. As long as this one key 1 remains depressed, no neighbored key is free for operation. This means in detail that, when a key 1 of the middle series is operated, the two outer series of keys are blocked, too.

If, however, a key 1 in one of the outer series is operated, only the neighbored middle series will be blocked, for only the balls of the one row of balls 10 are influenced then. The row of balls in FIG. 5 is embraced by the angled-off end 21 of an angle bar 11 (one each for both rows of balls following each ball movement which, due to the switching nose width, corresponds in each case to half the ball diameter. The angle bar 11 is accommodated below the balls and, upon actuation by the balls, controls with its other angled-off end 22 the switching plunger 12 which, in its turn, via the switching lugs 15 shown in FIG. 4, gets into operative connection with microswitches 14. The switching plunger 12 is mounted in frame 13, at which the microswitches 14 are secured. Switching plunger 12 cooperates with a spring 17 which immediately upon release of a key 1 provides for return of switching plunger 12, angle bar 11 (possibly both) and the displaced row of balls 10 (possibly both rows) into their initial positions.

As shown in FIG. 9, the angle bar 11 is positioned below the balls and controls with its angled-ofi end 22, switching plunger 12. Upon actuation by the balls the switching plunger 12 is displaced a short distance on its longitudinal axis. The switching lugs 15 which are attached to the switching plunger 12 make contact against the fixed leaf springs of the microswitches 14 thereby operating the microswitches.

Further details of the design are evident from FIG. 6. Frame 13 in its sleeve-shaped formations under each key 1 guides the compression springs 3 serving to reset the keys. An intermediate plate 7 is supported outwardly on said sleeve-shaped formations with their round openings, carrying a printed circuit board 9 between its lower side and frame 13. An insulating pin 5 supporting contact elements 6 at its upper end is secured to the inside of each of the keys. FIG. 6 shows two keys 1, the left-hand key 1 being in the rest position. Its insulating pin 5 and contact element 6 are drawn in another sectional view. The other, right-hand key 1 is depressed, its switching nose 2 has penetrated the row of balls 10 and thereby displaced balls as described.

Furthermore, this graphic representation shows the collars 19 of the intermediate plate 7, said collars 19 supporting the spring contacts 8. The junction ends of contacts 8 extend through the openings 20 in the circuit board 9 and also through corresponding openings in the intermediate plate 7. As indicated in FIG. 6, contacts 8 are there connected with the foil or face of the circuit board 9.

FIGS. 7 and 8 show top views of two different embodiments of the contact elements. Four contact springs 8 are shown in each case, spaced from one another by 90 each. In FIG. 7 they touch an annularly designed contact 6, whereby said four contact springs 8 are bridged. The contact element 6 in FIG. 8 is bipartite and upon contact making will bridge'the respective pairs of contact springs 8.

All the members of such a key selector switch are held together by bottom member 16 and keyboard 4. Springs 3 exert such an action on the insulating pins 5, their switching noses 2 molded to them and the contact arrangements, that any undesired play is eliminated, the keys return into their starting positions immediately upon release and the desired sequence of contact making in the two planes is ensured upon operation of a key 1.

Of course, it is possible without deviating from the idea of the invention to make the design so that the insulating pins 5 connected to the keys 1 support spring contact elements, while the opposite contacts are designed as, e.g., rigid pins being anchored in the intermediate plate and soldered to the foil or face.

What is claimed is:

1. A key selector switch for use in a telephone set comprising:

a frame 13 containing a plurality of openings aligned in rows;

a printed wiring board 9 operatively engaging and secured to said frame 13;

an intermediate plate 7 positioned upon said printed wiring board 9, said intermediate plate 7 including a plurality of sleeve members 19.extending upward therefrom and positioned coaxially with said openings;

a spring contact member 8 extending from said printed wiring board 9 and passing through said intermediate plate 7 upward and along one side of each of said sleeve members 19 and crossing over the upper end of and projecting inside of each of said sleeve member 19;

a key 1 positioned above each of said sleeve members 19, said key 1 further including a plunger 5 which extends downward into the openings of said sleeve member 19, said plunger 5 further including a contact member 6 selectively contacting said spring contact member 8;

a compression spring 3, said compression spring 3 included in said frame 13 which contacts said plunger 5 to normally hold said key 1 in an upward position;

a plurality of balls 10 positioned upon said intermediate plate 7 in at least one row parallel to said frame 13 openings and hence parallel to said keys 1; and

each of said keys including at least one switching nose 2 positioned outward from one side of said key 1 and being operatively positioned to engage at least one of the adjacent row of balls 10 upon depression of said key 1',

whereby when said key is fully depressed, said nose 2 will engage said adjacent row of balls 10 wherein said nose 2 will be positioned between two of said balls 10, thereby causing the remaining balls 10 to be displaced and removing all spaces between the balls thereby permitting another key 1 being depressed since its nose 2 cannot displace the balls 10 further.

2. The key selector switch of claim 1, characterized in that in the position of rest of the keys 1 the switching noses 2 form the stops of the keys within the housing.

3. The key selector switch of claim 1, characterized in that the switching noses 2 are so designed that, during their movement together with the respective depressed key 1, they can readily displace the balls 10 in that they are unilaterally provided with a bevel 18 in the direction of the clearance.

4. The key selector switch of claim 1, characterized in that below each of the two rows of balls there is disposed an angle bar 11 which with its angled-off end 21 engages behind the last ball of a row and with its opposite angled-off end 22 in the opposite direction cooperates with a common switching plunger 12 which is supported by a compression spring 17 and mounted in a frame 13 so that upon release of the key the switching plunger 12 and the angle bars 11 draw the balls 10 back into their starting positions by means of said compression spring 17.

5. The key selector switch according to claim 4, characterized in that said angle bar 11 is accommodated below said balls 10 and upon actuation by said balls 10, controls with its angled-off end 22 switching plunger 12, said switching plunger 12 is provided with lugs 15 which upon each key operation actuate switches secured to the frame 13.

6. The key selector switch of claim 1, characterized in that the switching noses 2 are so designed and cooperate with an intermediate plate 7 in a way such that they determine the downward stroke or travel of the key without causing a blocking thereby.

7. The key selector switch of claim 6, characterized in that the switching noses 2 are molded to insulating pins 5 inserted from below into the hood-shaped keys 1, or molded thereto, or bonded thereto, and that said insulating pins 5 are guided so as to be protected against rotation by the interaction between said insulating pins 5 and the guide sleeves l9 and the contact springs 8 in openings of the intermediate plate 7, said openings being provided with guide sleeves l9 and accommodating the contact springs 8 which project into said guide sleeves l9.

8. The key selector switch according to claim 7, characterizcd in that the insulating pins 5 at their upper ends support pressed-on, non-springs contact clamps or clips 6 which represent parts of rings and have each angled-off ends for being clampingly fixed and that said contact clamps 6 upon key operation cooperate with the contact springs 8 in that they electrically connect said contact springs 8 to each other.

9. The key selector switch of claim 7, characterized in that said insulating pins 5 at their upper ends support pressed-on, non-spring contact clamps or clips 6, e.g. in annular form, which upon key operation said clips 6 move integrally with said keys and cooperate with the contact springs 8 in that they electrically connect said contact springs 8 to each other.

10. The key selector switch of claim 9, characterized in that the contact elements connected with the circuit board 9 are formed as non-spring parts whose ends extend approximately in parallel to the direction of movement of the keys 1, and that spring contact elements, preferably bent in the form of an H, are provided on the insulating pins 5 and cooperate with the stationary contact elements. 

1. A key selector switch for use in a telephone set comprising: a frame 13 containing a plurality of openings aligned in rows; a printed wiring board 9 operatively engaging and secured to said frame 13; an intermediate plate 7 positionEd upon said printed wiring board 9, said intermediate plate 7 including a plurality of sleeve members 19 extending upward therefrom and positioned coaxially with said openings; a spring contact member 8 extending from said printed wiring board 9 and passing through said intermediate plate 7 upward and along one side of each of said sleeve members 19 and crossing over the upper end of and projecting inside of each of said sleeve member 19; a key 1 positioned above each of said sleeve members 19, said key 1 further including a plunger 5 which extends downward into the openings of said sleeve member 19, said plunger 5 further including a contact member 6 selectively contacting said spring contact member 8; a compression spring 3, said compression spring 3 included in said frame 13 which contacts said plunger 5 to normally hold said key 1 in an upward position; a plurality of balls 10 positioned upon said intermediate plate 7 in at least one row parallel to said frame 13 openings and hence parallel to said keys 1; and each of said keys including at least one switching nose 2 positioned outward from one side of said key 1 and being operatively positioned to engage at least one of the adjacent row of balls 10 upon depression of said key 1; whereby when said key is fully depressed, said nose 2 will engage said adjacent row of balls 10 wherein said nose 2 will be positioned between two of said balls 10, thereby causing the remaining balls 10 to be displaced and removing all spaces between the balls thereby permitting another key 1 being depressed since its nose 2 cannot displace the balls 10 further.
 2. The key selector switch of claim 1, characterized in that in the position of rest of the keys 1 the switching noses 2 form the stops of the keys within the housing.
 3. The key selector switch of claim 1, characterized in that the switching noses 2 are so designed that, during their movement together with the respective depressed key 1, they can readily displace the balls 10 in that they are unilaterally provided with a bevel 18 in the direction of the clearance.
 4. The key selector switch of claim 1, characterized in that below each of the two rows of balls there is disposed an angle bar 11 which with its angled-off end 21 engages behind the last ball 10 of a row and with its opposite angled-off end 22 in the opposite direction cooperates with a common switching plunger 12 which is supported by a compression spring 17 and mounted in a frame 13 so that upon release of the key the switching plunger 12 and the angle bars 11 draw the balls 10 back into their starting positions by means of said compression spring
 17. 5. The key selector switch according to claim 4, characterized in that said angle bar 11 is accommodated below said balls 10 and upon actuation by said balls 10, controls with its angled-off end 22 switching plunger 12, said switching plunger 12 is provided with lugs 15 which upon each key operation actuate switches secured to the frame
 13. 6. The key selector switch of claim 1, characterized in that the switching noses 2 are so designed and cooperate with an intermediate plate 7 in a way such that they determine the downward stroke or travel of the key without causing a blocking thereby.
 7. The key selector switch of claim 6, characterized in that the switching noses 2 are molded to insulating pins 5 inserted from below into the hood-shaped keys 1, or molded thereto, or bonded thereto, and that said insulating pins 5 are guided so as to be protected against rotation by the interaction between said insulating pins 5 and the guide sleeves 19 and the contact springs 8 in openings of the intermediate plate 7, said openings being provided with guide sleeves 19 and accommodating the contact springs 8 which project into said guide sleeves
 19. 8. The key selector switch according to claim 7, characterized in that the insulating pins 5 at their upper ends support pressed-on, non-springs contact clamps or clips 6 which represent partS of rings and have each angled-off ends for being clampingly fixed and that said contact clamps 6 upon key operation cooperate with the contact springs 8 in that they electrically connect said contact springs 8 to each other.
 9. The key selector switch of claim 7, characterized in that said insulating pins 5 at their upper ends support pressed-on, non-spring contact clamps or clips 6, e.g. in annular form, which upon key operation said clips 6 move integrally with said keys and cooperate with the contact springs 8 in that they electrically connect said contact springs 8 to each other.
 10. The key selector switch of claim 9, characterized in that the contact elements connected with the circuit board 9 are formed as non-spring parts whose ends extend approximately in parallel to the direction of movement of the keys 1, and that spring contact elements, preferably bent in the form of an H, are provided on the insulating pins 5 and cooperate with the stationary contact elements. 